Metal slat box spring assembly

ABSTRACT

A box spring assembly comprising a base frame, a series of metal slats mounted upon the base, and a series of springs connected at their lower ends to the metal slats and tied together by helical wires or wire grids at their upper ends. The metal slats are preferably made from sheet metal shaped so as to form a rigid rib which extends for the length of the slats.

Umted States Patent 1191 1111 3,9 Higgins Nov. 4, 1975 METAL SLAT BOXSPRING ASSEMBLY 3,612,505 10/1971 5/247 3,680,157 8/1972 5/247 [75]Inventor. Larry Higgins, Carthage, Mo. 3,725,965 4/1973 H 5047 [73] A iLegge & n Incorporated 3,750,201 8/1973 Usami 5/263 Carthage, Mo.Primary ExaminerPaul R. Gilliam [22] Filed 1974 Attorney, Agent, orFirm-Wood, Herron & Evans 21 Appl. No.: 461,745

[57] ABSTRACT [52] US. Cl 5/264 R; 5/246; 267/93 51 lm. c1. A47C 23/02;A47C 23/04 box spr'ng assembly a base frame a [58] Field of Search 5 246263 264 R 245 metal slats mmmted the base and a genes of springsconnected at their lower ends to the metal slats and tied together byhelical wires or wire grids at [56] References Cited their upper ends.The metal slats are preferably made from sheet metal shaped so as toform a rigid rib UNITED STATES PATENTS which extends for the length ofthe slats. 773,312 10/1904 DArcy 5/264 R 3,497,880 3/1970 On 5/247 1Claim, 6 Drawing Figures U.S. Patent Nov. 4, 1975 Sheet 2 of4 3,916,463

U.S. Patent Nov. 4, 1975 Sheet4 of4 3,916,463

METAL SLAT BOX SPRING ASSEMBLY This invention relates to beddingfoundations, or so called box springs of the type commonly employed as afoundation base for a bed mattress.

lBox spring assemblies generally comprise a wooden base frame acrosswhich extend a plurality of transverse wooden slats. A plurality ofhelical springs are generally mounted atop these wooden slats and thetops of the springs are generally interconnected by a series of wires,either in the form of helical wire extending between the topconvolutions of the helical springs, or welded wires extending betweenand interconnecting the tops of the springs. The assembly is completedby placing a cushion or fabric pad over the top of the assembly and thenenclosing it within upholstered fab- The manufacture of theseconventional box springs involves a large percentage of hand or manuallabor, which the bedding industry has tried to minimize or eliminatewhenever it became economical to do so. Generally, though, those effortsto automate the manufacture of box springs have met with limited successbecause the construction of commercial box springassemblies does notlend itself to automatic assembly and manufacture.

In general, the quality of the box spring assembly and the price whichit commands on the market is a function of the firmness of the assemblyand its expected useful life. This latter quality is measured in termsof its ability to withstand abuse in use and to measure that quality ofdurability, special machines have been developed and standardized in theindustry.

Firmness is generally a function of the quantity of metal employed inthe helical springs of the assembly. In other words, the heavier gaugemetal wire employed in the springs of the assembly and the more helicalsemployed over a selected area, the more firm is the assembly andtherefore the higher price it commands as a quality product.

It has been a primary objective of this invention to provide an improvedbox spring assembly which is of high quality both in firmness and indurability, but with fewer helical springs and of smaller gauge wire inthe helical springs than has been heretofore possible.

Another objective of this invention has been to provide a box springwhich is firm and which has a long projected useful life but with lessmetal in the springs than has been heretofore possible.

It has been another objective of this invention to provide a box springassembly which meets the highest standards of firmness and useful lifewhile still providing an assembly which may be manufactured andassembled with a minimum of hand labor.

The box frame assembly of this invention which accomplishes theseobjectives comprises a wooden bottom frame to which are connected metalslats so configurated as to be very rigid and having spring connectorsformed therein so that the springs may be attached to the metal slats bya machine or with a minimum of manual labor. In the preferredembodiment, the metal slats are formed from sheet metal and have arigidifying rib shaped into the metal so that the slat, even though ofminimum metal content, is very rigid.

The primary advantage of the box spring assembly of this invention whichincorporates this metal slat in the bottom of the box spring is that itprovides a more rigid bottom for the assembly than is provided by wooden2 slats. Consequently lighter springs may be used in the metal slattedbox spring than may be employed in comparable firmness wooden slat boxspring.

In one preferred embodiment of the invention, the springs are conicallyshaped helical springs in which the last or lower convolution of thespring is retained attached to the slat by forcing the last convolutionof the spring into a flat horizontal plane of a slot formed in the slat.This results in the spring being stressed and being retained in theslots by the stress on the spring.

In another preferred embodiment of the invention, the springs are singlestrand modular springs which extend transversely across the assembly andhave spring units formed into the single strand as illustrated anddescribed in US. Pat. No. 3,725,964. In this modification, each springis attached to the metal slat by flaps formed or cut and bent from themetal slat and bent over a section of a spring.

These and other objects and advantages of this invention will be morereadily apparent from the following description of the drawings inwhich:

FIG. 1 is a top perspective view of a box spring assembly incorporatingthe invention of this application.

FIG. 2 is a side perspective view of a portion of the box springassembly of FIG. 1.

FIG. 3 is a diagrammatic side view, partially in section, of a metalslat and helical spring illustrating the condition of the spring priorto assembly of the spring and slat.

FIG. 4 is a view similar to FIG. 3 but illustrating the condition of thespring and the slat after attachment of the spring to the slat.

FIG. 5 is a perspective view of a portion of a second modification of abox spring assembly incorporating the invention of this application.

FIG. 6 is a perspective view of a portion of a third modification of abox spring assembly incorporating the invention of this application.

Referring first to FIGS. 1 and 2, it will be seen that the box spring 10comprises a bottom frame 11, a top grid 12 surrounded by a border wire13, a series of helical springs 14 extending between the top grid 12 anda plurality of transverse metal slats 15 and a fabric cover 9. The endsof the slats 15 are secured to the wooden frame 11 by nails or staples16.

The bottom frame comprises a pair of side boards 17, 18 nailed orotherwise fixedly secured to a pair of end boards (only one of which isshown at 19). The metal slats 15 extend transversely between the sideboards 17 and 18.

The border wire 13 is located immediately above and is spaced from theouter circumferential edge of the bottom frame 11 of the assembly 10. Itis connected to and supported by the wooden frame through the helicalspring 14, as is explained more fully hereinafter.

The top grid 12 comprises a series of parallel transverse wires 30 and aparallel series of longitudinal wires 31. The ends of allthese-transverse and longitudinal wires 30, 31 of the top grid aresecured to the border wire 13 by being welded to the border wire andwrapped around it, as illustrated at 36. The longitudinal and transversewires 30, 31 of the top grid may be welded at all of their intersectionsso as to further stabilize the box spring assembly and increase itsfirmness as well as its resistance to side sway.

Referring to FIG. 2, it will be seen that there are a plurality of threepronged channels 40 transversely spaced across each of the transversewires 30. Each one of the transverse channels 40 is open to the bottomof the top grid. Each of these three pronged channels 40 comprises apair of reversely bent fingers or prongs 41, 42 located in a commonvertical plane and interconnected by transverse bends 43, 44 to acentral reversely bent prong or finger 45. The central finger is alsolocated in a vertical plane but is spaced from the vertical plane of thefingers 41, 42 so that a channel is defined between them. The uppermostconvolutions 20 of the springs 14 are received within these channels 40and are locked therein by bending the central finger 45 beneath the wireof the top convolution 20. A more detailed description of theconfiguration of the three pronged channels 40 may be found in the aboveidentified US. Pat. No. 3,725,965.

Referring now to FIGS. 2, 3, and 4, it will be seen that in thepreferred embodiment each of the helical springs 14 is conical in shapeand has a lower end convolution 47, an upper end convolution 20, and aseries of intermediate convolutions of increasing diameter. In theillustrated preferred embodiment, the lower convolution 47 of thesprings 14 has its endmost portion 48 bent out of a spiral configurationso that it is located closely adjacent the convolution 49 immediatelyabove it. The uppermost convolution 20 is bent out of the spiralconfiguration into a single horizontal plane and has its end 50 formedinto a knot or pigtail which is wrapped around the upper end of the nextadjacent convolution 21. This upper convolution forms a planar circularconvolution for attachment to the grid 12.

While the springs 14 have been illustrated in this preferred embodimentas being conical in overall configuration, the shape forms no part ofthe invention of this application, and the springs could, as well, beshaped as an hourglass with large diameter convolutions at the ends andsmaller diameter convolutions at the center, or the springs could becylindrical as is common in many box spring assemblies.

The metal slats are formed from sheet metal which is shaped asaninverted U and has horizontal flanges 51, 52 extending outwardly fromthe bottom of the inverted U-shaped central section 53. This invertedU-shaped central section forms a rigidifying rib which extends for thefull length of the slat 15. As may be seen most clearly in FIG. 2, theends of the flanges 51, 52 rest atop and are secured to the top of theside boards 17 and 18. The securement in the preferred embodimentconsists of staples 16 which are nailed through an aperture in the endof the slats and into the end boards 17 and 18.

In order to secure the springs 14 to the slats, each slat has aplurality of horizontal slots 55 formed in it. The spacing of theseslots is identical to the centerline spacing of the springs 14, as maybest be seen in FIG. 2. In order to secure and retain the lowermostconvolution 47 of the springs within the slots 55, the slots are locateda sufficient distance beneath the top 56 of the slat that when thelowermost convolution is inserted into the slot 55, it causes thedistance D (FIG. 3) between the lowermost convolution 47 and the nextadjacent convolution 49 to be increased to the distance D' (FIG. 4) soas to place the last two convolutions of the spring under stress. Thisstressing of the lowermost convolutions of the spring and the forcing ofthe generally nonplanar lowermost convolution 47 into a horizontalplanar configuration retains the spring under stress and assembled tothe slat. Irrespective of how the box spring assembly is subsequentlyloaded or shifted, the last two 4 convolutions remain under stress andcannot be displaced from the slots 55. The only way that the springs canbe dislodged from the slots 55 is by physically engaging that portion 57of the spring which protrudes from the slot and pushing it in thedirection indicated by the arrow 58 in FIG. 4. Of course when the boxspring assembly is covered by padding and upholstery 9 (FIG. 1) there isno possibility of anyone engaging the point 57 of the lower convolution47 and physically disconnecting it from the slat.

The primary advantage of the box spring assembly of FIGS. 1-4 resides inthe rigidity of the box spring assembly imparted by the configuratedmetal slats 15 and the ease with which the springs may be secured to theslats. This added rigidity is greater than that of conventional woodenslats of equal cost so that with lighter springs the box spring assemblydepicted in FIGS. 1-4 has the same rigidity as that of the conventionalwood slat box spring but with springs 14 of heavier gauge metal or ingreater numbers.

Referring now to FIG. 5, there is illustrated a second preferredembodiment of a box spring assembly incorporating the invention of thisapplication. In general, this box spring assembly is very similar tothat depicted in FIGS. 1-4. It departs from that first preferredembodiment in that it utilizes a different type of spring in lieu of thehelical spring 14 of the first embodiment, and it utilizes a differentform of connector between the spring and the metal slat. Specifically,it substitutes a modular single wire spring 60 for a series of helicalsprings 14.

The modular spring unit 60 of this second embodiment is completelydescribed in Smith et al US. Pat. No. 3,725,965, which issued on Apr.10, 1973 and which is assigned to the assignee of this application.

In this embodiment, each modular spring unit 60 comprises a singlestrand of wire within which there are formed several individual springs.In the illustrated embodiment, there are two end springs 61 (only one ofwhich is illustrated) formed in each modular unit 60, as well as severalintermediate springs 62 (only one of which is shown for each modularspring unit 60). Each of these end springs and intermediate springs isseparated from the adjacent spring by a generally horizontally extendingstraight section 63 of the wire strand.

The end springs 61 each comprise a straight vertical leg 65 whichextends downwardly from the endmost straight section 63 of the wirestrand. This section terminates at its lower end in an arcuate section66, the lower end of which is bent into a closed loop 67. In theillustrated preferred embodiment, the arcuate section 66 is bent out ofthe vertical plane of the leg 65 through an angle of approximately 60.It is this arcuate section which provides the resiliency of the endsprings 61. The loop 67 at the end of the spring 61 is secured to theside board of the frame by a staple 68.

The intermediate springs 62 in each of the modular spring units 60 eachcomprise a vertical leg 70 which extends downwardly from one of thegenerally straight, horizontal co-linear sections 63, a loop section 71located at the lower end of the vertical leg 70, and a vertical 72 whichextends back upwardly from the loop 71 to one of the straight sections63. In the illustrated emspring.

The angle defined by the bend in the individual springs is not criticalto the operation of the invention. In fact, an angle which variesanywhere from approximately to and through 90 is bound to besatisfactory so long as sufficient radius is provided on that portion74, 75 of the bend which interconnects the loop 71 to the legs 70, 72.This angle and radius of the are within which it is located aredeterminative of the resiliency of the spring.

In the illustrated embodiment, the outermost ones of the intermediatesprings in each modular spring unit 60 are spaced different distancesfrom the ends of the modular spring unit. Consequently, the modularspring units may be used in pairs, with one unit reversed end for endfrom the other and with arcuate bends 74, 75 of the individual modulesfacing each other. When paired in this manner, the intermediate springs62 of one of the pairs are equidistantly spaced from or interleavedthrough the intermediate springs of the other modular spring unit of thepair. Consequently, there is a very even distribution of resiliency ofthe total box spring assembly.

In this embodiment, the springs 62 of the individual modular springunits 60 are connected to the metal slats 80 by sections of the slatswhich are punched from the sidewalls of the U-shaped portion so as toform tabs 81 which are bent over the loop sections 71 of each individualspring 62. This connection of the springs to the metal slat provides aninexpensive connector which facilitates automatic manufacture of the boxspring assembly.

In this second preferred embodiment, as in the first, the formed sheetmetal slats provide added firmness to the box spring assembly which isnot achievable with conventional soft wood slats now commonly in use.Additionally, the connectors which are formed in the slats, and whichhave been illustrated in the preferred embodiments of the invention,facilitate automated manufacture of the box spring assembly.

Referring now to FIG. 6 there is illustrated still a third embodiment ofthe invention of this application. In general, this embodiment is verysimilar to the embodiment illustrated in FIG. 5, and accordingly, thoseportions of this embodiment which correspond to the embodiment of FIG. 5have been given corresponding numeral designations but followed by aprime mark.

This FIG. 6 modification distinguishes from the mod ification of FIG. 5principally in that it substitutes fishmouth spring units 90 for the endsprings 61 of the modular spring units 60. Applicant has found that insome applications, additional support in the form of fishmouth springsbetween the border wire 91 of the unit and the wooden boards of thebottom frame 11 better reinforces the edgewise portions of the springassembly and precludes the border wire from being deformed to such anextent that it takes a permanent set.

Each fishmouth spring unit 90, of which there are several located aroundthe periphery of the spring assembly, comprises a single strand of wireconfigurated so that each stand defines a pair of transversely spacedfishmouth springs 92, 93 interconnected by a horizontally extendingupper section 94 of the unit 90. The upper section 94 is generallyU-shaped in configuration and is wired or clipped to the border wire 91by wrappings or clips 95. Between the wraps or cliips 95, the uppersection 94 of the spring is offset inwardly be- 6 neath the horizontalstraight sections 63 of the modular springs and beneath the upper wiregrid 12. Because of this offset, the fishmouth spring units support thelateral extremities of the modular springs 60 as well as the edge borderwire 91.-

From the wrapping or connection of the spring unit to the border wire,each fishmouth spring 92, 93 has a straight section 96 extendingvertically downwardly. This straight section 96 is connected at itslower end to an inwardly turned horizontally extending section 97. Atthe end remote from the vertical section 96, the horizontally extendingsection is bent downwardly at an angle of approximately 45 to ahorizontally extending torsion bar section 98. The end of the torsionbar section 98 remote from the inclined section 99 then is bentdownwardly and outwardly at an angle of approximately 45 to thehorizontal plane of the top surface of the wooden border frame 11'. Thelower end of this second inclined section 100 terminates in a U- shapedsection 101 which is stapled to the top surface of the wooden frame bystaples 102.

Each of the spring units 92, 93 is referred to as a fishmouth springbecause when viewed in side elevation the two inclined sections 99, 100extend in opposite directions from the torsion bar 98 and give theappearance of an open V-shaped fishmouth. It is this open fishmouthsection which is resilient and which enables the edge portion of thespring unit to be deflected but still reinforced by a substantialspring.

While I have described only a single preferred embodiment of myinvention, persons skilled in the art to which it relates will readilyappreciate numerous changes and modifications which may be made withoutdeparting from the spirit of my invention. Therefore, I do not intend tobe limited except by the scope of the following appended claims.

l-laving described my invention, I claim:

1. A box spring assembly comprising a generally rectangular bottomframe,

a plurality of spaced parallel cross slats extending between andconnected to opposite sides of said rectangular bottom frame,

a plurality of helical springs each terminating at one end in agenerally planar lower round and at the opposite end in a generallyplanar upper round,

means interconnecting and securing said upper rounds of said helicalsprings in a common plane,

each of said slats being formed from metal shaped to define transverselyspaced flat bottom surfaces resting upon said opposite sides of saidbottom frame and a transversely extending rib having opposed spaced sidewalls and a top surface located between said fiat bottom surfaces, and

connector means formed in said ribs of said slats for connecting saidlower rounds of said helical springs to said slats, said connector meanscomprising slots formed in said opposed walls of said ribs of saidslats, said bottom rounds of said helical springs being frictionallysecured within said slots by forcing said bottom rounds of said helicalsprings away from the adjacent helical round as said bottom round isinserted into a slot and by maintaining said bottom and adjacent roundsof said spring under stress with said bottom round physically contactingsaid slot and the adjacent round physically contacting said top surfaceof said rib.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 16, 6

DATED 1 November 4, 1975 INVENT (S) Larry Higgins It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Col. 1, line 11, "wire" should be -wires- Col. 1, line 48, after"spring" insert assembly- Col. 2, line 15, "3,725,964" should be--3,725,965- Col. 4, line 18, "wood" should be -wooden Col. 4, line 62,after "vertical" insert leg- Col. 5, line 16, after "with" insert -the-Q Col. 5, line 61, "stand" should be -strand- Col. 5, line 66, "cliips"should be --clips En'gncd and Scaled this second Day of March 1976 I[SEAL] Attest:

RUTH c. MASON I c. MARSHALL DANN Arresting Officer Commissioneroj'Parents and Trademarks

1. A box spring assembly comprising a generally rectangular bottomframe, a plurality of spaced parallel cross slats extending between andconnected to opposite sides of said rectangular bottom frame, aplurality of helical springs each terminating at one end in a generallyplanar lower round and at the opposite end in a generally planar upperround, means interconnecting and securing said upper rounds of saidhelical springs in a common plane, each of said slats being formed frommetal shaped to define transversely spaced flat bottom surfaces restingupon said opposite sides of said bottom frame and a transverselyextending rib having opposed spaced side walls and a top surface locatedbetween said flat bottom surfaces, and connector means formed in saidribs of said slats for connecting said lower rounds of said helicalsprings to said slats, said connector means comprising slots formed insaid opposed walls of said ribs of said slats, said bottom rounds ofsaid helical springs being frictionally secured within said slots byforcing said bottom rounds of said helical springs away from theadjacent helical round as said bottom round is inserted into a slot andby maintaining said bottom and adjacent rounds of said spring understress with said bottom round physically contacting said slot and theadjacent round physically contacting said top surface of said rib.